The Gordon Conference on Second Messengers and Protein Phosphorylation in June, 1989 will concentrate on the structure and function of proteins, receptors, G proteins, effector enzymes, and on channels which transmit extracellular signals across the plasma membrane. Responses to second messengers, especially in relation to growth and differentiation. Over the past year, there has been an increasing awareness of the parallelism in signalling and second messenger systems between mammalian cells and lower organisms in which genetic manipulation can be more easily accomplished. The design of the Conference will try to bring out the lessons to be learned from a variety of biologic systems by including presentations on mammalian cells, as well as on Drosophilia, yeast and Dictyostelium. The Conference should provide a lively forum for exchange of information, ideas and prospects for the future. All participants will be encouraged to present posters describing their work. Last year, approximately 80% of the participants in the Conference presented data either in posters or as speakers. Such active participation by the conferees encourages discussion and fosters new interactions. The sessions planned for the 1989 Conference are: 1) receptor families; 2) structure and function of enzymes which generate second messengers; 3) guanine nucleotide binding proteins; 4) structure and regulation of ion channels; 5) regulation of signalling systems in growth and differentiation; 6) protein kinases and phosphorylation; 7) regulation of signalling systems in yeast and Dictyostelium; 8) use of transgenic animals to analyze complex biological systems; and 9) localization of membrane proteins and signalling systems; regulation of exocytosis and functions of small GTP binding proteins.